Apoptotic Cell Death and p53 Expression in Leiomyosarcoma of Soft-Tissue Origin

Leiomyosarcoma (LMS) of soft-tissue origin was studied on the expression and the biological significance of apoptosis in relation to p53 oncoprotein. Immunohistochemical analysis was performed initially on the paraffin-embbeded sections taken from 29 surgical tissues (20 cases) including 9 recurrent/metastatic tumors. The results are as follows: A positive correlation was observed between the p53 indices (PIs) and the proliferative markers designated by Ki-67, PCNA and MCM2, both of which increased significantly in the high-grade malignant LMS much more than in the low-grade one (P < 0.001). Apoptotic cells were detected by the TUNEL method and evaluated as the apoptotic index (AI). A high AI-level was shown in the high-grade malignant LMS, especially in cases of the recurrent/metastatic sites in comparison with the tumors of the primary site (P < 0.05). The AI was statistically higher in the p53-positive cases of high-grade malignant LMS than in the p53-negative cases of low-grade malignant LMS. In conclusion, apoptotic activity paralleled the overexpression of p53 protein along with an increasing grade of malignancy and may be related intimately to the increased malignant potential, especially to recurrence/metastasis.